Audi Repair: Audi temperature sensor?, coolant temperature sensor, engine coolant temperature sensor

Question
Dear Greg,
My 1996 audi a4 2.8q doesnt start when it is really hot outside. it will start in the morning when it is cooler or if i park it in the shade, usually. When its not starting, you can tell that the battery and the starter are all working well. Sometimes it takes up to an hour to start. A mechanic diagnosed that the water temperature sensor needs to be changed. I took the car to my usual mechanic who said that by the way it doesnt start, it has a lot more problems than that temperature sensor. He inferred that he should do a diagnosis (and charge me for that) and

My question (finally) is: Could it be just that sensor or is my mechanic trying to hose me? Thanks.

Answer
hello
I will star with temperature sensor (ECT - engine coolant temperature sensor) because on Audis if they go bad, most of the time they read -40 C , so the ECM will damp so much fuel that the car will not star. This is the first step to start.
good luck                 pltech